Incandescent electric lamp.



PATENTED OCT. ll, 1904.

J. R. LOVEJOY.

- NGANDESCENT ELECTRIC LAMP.

APPLICATION FILED DEO. l1, 1901.

N0 MODEL.

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UNITED vSTATI-3s Patented October 11, 1904.

APATENT OFFICE.

JESSE R. IJOVEJOY, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GEN- ERALELECTRIC COMPANY, A CORPORATION OE NEW YORK.

INCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 771,988, dated October11, 1904.

-Application filed-December 1l, 1901. Serial No. 85,478. (No model.)

To @ZZ whom t may con/cern:

Be it known lthat I, Jnssn R. LovnJoY, a

citizen of the United States, residing at Schenectady, county ofSchenectady, State of New YorlLhave invented certain new and usefulImprovements in Incandescent Electric Lamps, of which the following is aspecification.

Much annoyance is occasioned by the burning out or rupture of laments ofincandescent lamps when such lamps are arranged several in series acrossrailway or other circuits. For example, in street-cars it is common touse one or more groups of five each, connected f from trolley to ground.Evidently the rupture or burning out of one filament puts out the wholegroup, and if but one group is installed the car is left in totaldarkness until the conductor replaces a fresh lamp. It is the object ofmy invention to mitigate this annoyance by arranging a lamp providedwith a double filament, so that a new filamentV may be cutin, and thusrestore the illumination of the car by a simple manipulation of thelamp. Again, many consumers desire a lamp for use in bedrooms,sick-rooms, &c., which may be burned with very low candle-power or fullbrilliancy at will. My invention lends itself with equal advantage tosuch use.

In carrying out my invention I proceed by providing the lamp with twofilaments and three terminals, one of which terminals is the metallicshell or screw base if it be an Edison type of lamp, and the other twoterminals are insulated metallic contacts mounted on the under side ofthe lamp-base. The two filaments may be of equal or unequal resistance,-

accordingly as it is desired to employ the lamp for car illumination, asabove referred to, or for domestic purposes for night use. I providealso a socket-plug, which may be called a transfer-plug, by whichcurrent may be led from the terminals in the receiving-socket, mountedon the roof of the car or on the wall of a residence, to either of thetwo filaments. The plug is so organized that a common conducting-shellacts as a carrier or connector between the shell-contact of thereceiving-socket and the shell of the lamp-base. It has also aninsulated center-pin to connect at one end with the tongue terminal ofthe socket and at the other end by an elastic contact having a.contact-face eccentric to the axis of the transfer-plug with either ofthe insulated lampcontacts. The insulated contacts of the lampvbase maybe shifted alternately into engagement with the elastic contact of thetransferplug, thereby lighting up either filament at will. If thelamp byreason of a break of one `filament becomes extinguished, the other fila-`ment may be cut into circuit by a simple rotation of the lamp on itsaxis, and if when used as anight-lamp it be desired to cut down theillumination the bulb is partially rotated, so as to cut in the filamentof lower candlepower. rIhe transfer-plug consists of a simple shell,which is slightly larger in diameter at one end than at the other,adapted to screw into the receiving-socket at one end and at the otherend to receive the lamp-base.

The several features of novelty will be more fully hereinafterdescribed, and will be detinitely indicated in the claims appended tothis specification.

In the accompanying drawings, which illustrate my invention, Figure l isa sectional view of a lamp, a transfer-plug, and socket;

and Fig. 2 a detail view of the transfer-plug.

designed for use with the Edison lamp, the

plug-shell may be a single-threaded shell slightly contracted at oneend, as indicated in Fig. 2, and provided with a plug of insulatingmaterial 2, such as porcelain, plaster-ofparis, or other suitablecompound, through the center of which passes a conducting-pin 3,terminating in the elastic contact 4, the engaging face of which is offcenter with respect to the axis of the plug. This contact may be fixedto the post or may be mounted so as to be clamped by a nut, as indicatedin Fig. 2, permitting its adjustment to different angular positions.

The lamp is provided with a double lilament 5 5, one pair of terminalsof which lead out through a wire 6 to the threaded shell 7 on thelamp-base, the other ends of the iilaments leading through sealed-inwires, as usual, to separate insulated contacts 8 8, secured in thecement or porcelain which fastens the neck of the lamp to its base.These contacts are symmetrically placed with respect to the lamp-axisand both off center, the distance being gaged so that when the lamp isscrewed into the transfer-plug the contacts will cross the face of thespring 4 and make contact therewith.

9 represents a familiar type of socket largely in use on trolley-carsand is shown as connected up with a pair of leads in the trolleycircuit.The socket contains screw connections with the leads, putting them incommunication, respectively, with a threaded metal shell 10 and a metalcenter-pin 11. rIhus when the transfer-plug is screwed into the socketthe former extends the contact from the screw-shell in the socket to theshell of the lamp-base and from the contact-pin in the socket to one ofthe insulated contacts on the lamp-base.

In the position shown in Fig. 1 the iilament 5 is receiving current.sirable or necessary to cut in the other lilament a partial rotation ofthe lamp on its axis breaks connection between the contact-spring 4 andcontact 8L and effects connection with contact 8. This may be done by aquick movement, which will prevent damage from arcing. The spring 4should be given a sufcient range of elasticity to permit of suchadjustment; but, if preferred, it may be made quite stiftand shiftedangularly in position to effect a new contact.

It is evident that for car use the conductor is not obliged to carry anextra supply of lamps, since in case of extinguishment of the lightsthrough fracture or burning out of a iilament it is only necessary forhim to turn In case it becomes dethe bulb to restore the lights. It willfurther be evident that no changes in the wiring of the car arerequired. The same advantage would also inhere in the application todomestic illumination. 1

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent of the United States, is-- 1. The combinationwith a double-filament' lamp having a shell-contact to which bothfilaments are connected and two eccentricallypositioned insulatedcontacts on the end of its base for the respective filaments, of aseparable transfer-plug to engage a standard socket, said plug extendingthe shell-contact of the socket to the shell-contact of the lamp-base,and having a contact mounted eccentrically to engage either contact onthe base according' to their angular position.

2. The combination with a double-filament lamp having a shell-contact towhich both filaments are connected and insulated end contacts for therespective iilaments set a like distance from the lamp-axis, of aseparable transfer-plug having a shell-contact and a springcontact inposition to intercept either lampcontact according to their angularposition.

3. The combination with a double-filament lamp having a threaded metalbase and two insulated contacts for the respective ilaments mountedeccentrically by a like distance, of a separable transfer-plugcomprising a threaded shell to connect interiorly with the socket at oneend, and exteriorly with the lamp-base at the other, and aspring-contact to transfer the center contact of the socket to eitherfilamentcontact by rotating the lamp-bulb.

In witness whereof I have hereunto set my hand this 10th day ofDecember, 1901.

JESSE R. LOVEJ OY.

Witnesses:

BENJAMIN B. HULL, HELEN ORFoRD.

